This invention relates to cardiac arrhythmias, and more particularly to a tissue ablation device and methods of using such a device.
Atrial fibrillation is the most common sustained arrhythmia encountered in clinical practice and affects over 2 million Americans. Atrial fibrillation is often initiated by rapidly firing triggers located in the pulmonary veins. One method for treating atrial fibrillation includes placement of a catheter adjacent to the arrhythmogenic substrate that contains the trigger or electrically connects the trigger to the atrium, followed by subsequent ablation of the tissue containing the trigger. These triggers may only discharge intermittently, which makes it difficult to precisely position the catheter with respect to the trigger location and precisely ablate the tissue necessary to eradicate the trigger.
The anatomy of the pulmonary veins is complex, and technical limitations make localizing and eliminating pulmonary vein potentials difficult. Multiple procedures, therefore, are often required to precisely locate the triggers in the pulmonary veins. Once the triggers are located, complications often arise during the ablation procedure. For example, ablation within the pulmonary vein increases the risk of pulmonary vein stenosis. In addition, effective monitoring of the pulmonary vein (e.g., assessment of edema, thrombosis, and/or narrowing) during energy delivery remains difficult.
Conventional catheters, including a Laso catheter and various balloon catheters, have been used in both diagnostic and therapeutic applications. However, using these conventional catheters it is difficult to engage the target tissue, either circumferentially or focally. These devices also have a propensity for entering the pulmonary vein, which has further limited their usefulness in the treatment of atrial fibrillation.
The invention provides for a tissue ablation device having a retractable and deployable umbrella body. The umbrella body includes ablation elements for circumferentially engaging and ablating a target tissue. The invention further provides of methods of using such a tissue ablation device for treating cardiac arrhythmias.
The umbrella body is an adjustable, compliant cone-shaped member that may be deployed over a wide range of working diameters. The ablation elements attached to the umbrella body can therefore conform to the geometry of the pulmonary vein ostium and provide circumferential contact, which permits more accurate ablation procedures.
The deployable umbrella body allows the tissue ablation device of the invention to be configured in a wide variety of ways. For example, the ablation elements on such a device can be configured for circumferential, focal or segmental ablation. In addition, the device may be used to simultaneously record pulmonary vein potentials from various depths within the vein to facilitate determination of successful ablation. The adjustable deployment of an umbrella body allows for a wide variety of patients or of vessels within a single patient to be treated with just one or a few tissue ablation devices.
In one aspect, the invention provides for a tissue ablation device including a catheter body and at least one deployable umbrella body attached to the distal portion of the catheter body. Generally, the catheter body has a proximal portion and a distal portion, wherein the proximal and distal portions define a longitudinal axis. The umbrella body generally includes a plurality of radial splines and at least one ablation element, wherein the at least one ablation element is attached to at least one of the plurality of splines. Each of the splines typically has a distal end and a hinged end, wherein the hinged end is attached to the catheter body.
A tissue ablation device of the invention can further include a deployment element connected to the splines, wherein the deployment element is capable of adjustably deploying the umbrella body. Ablation elements can be attached to the splines at the distal end of the splines or at a position medial to the distal end and the hinged end of the spline. A deployment element can include a slideable deployment/retractor collar that circumscribes the splines and can further include connector rods linking the slideable deployment/retractor collar to the splines. A tissue ablation device of the invention can have a deployment element that includes a slideable deployment/retractor collar circumscribing the splines, which further include a deployment member for adjustably sliding the deployment/retractor collar along the longitudinal axis of the catheter body. A tissue ablation device of can have a deployment member that comprises a slideable member that is a contiguous body with the splines. In one embodiment, the slideable member is within a central lumen of the catheter body. According to the invention, the hinged end of the splines can be attached to the catheter body or can be attached to a central hub on the catheter body.
An umbrella body on a tissue ablation device of the invention can further comprise at least one circumferential loop or loop segment attached to the plurality of splines. An umbrella body can include one or more (e.g., two) circumferential loop attached to the plurality of splines. According to the invention, a loop segment can be a contiguous member of the spline. Further, loop segments can be hinged. In addition, circumferential loops or loop segments can be conductive, or can have ablation elements attached to at least one of the circumferential loops or loop segments. An umbrella body can further comprise membranous material attached to one or more sets of adjacent splines. Such membranous material can comprise at least one ablation element or itself can be conductive.
It is a feature of the invention that the distal ends of the splines can move through an angle xcex1 relative to the longitudinal axis of the catheter body. The angle xcex1 can be between about 0xc2x0 and about 90xc2x0 or between about 0xc2x0 and about 180xc2x0 relative to the longitudinal axis of the catheter body.
An ablation element suitable for use in the invention can be a cryogenic element, an ultrasound element, a light-emitting element, a microwave element, a thermal element, a laser, chemical fluid, or an electrode element. According to the invention, the ablation element can be an electrode. An electrode can be a band electrode, a spiral electrode, or a coil electrode.
A tissue ablation device of the invention can further include at least one of a monitoring device or a sensing element attached to the tissue ablation device. Representative monitoring devices and/or sensing elements include an intracardiac echo device, an ultrasound transducer assembly attached to the tissue ablation device, and electrodes.
In another aspect, the invention provides a tissue ablation device for treating atrial arrhythmia, can include a catheter body, wherein the catheter body with a proximal portion and a distal portion, wherein the proximal and distal portions define a longitudinal axis; and at least one deployable umbrella body located at the distal portion of the catheter body, wherein the umbrella body comprises. An umbrella body includes a plurality of splines attached to the catheter body, and at least one ablation element, wherein the at least one ablation element is attached to at least one of the plurality of splines. According to the invention, the splines can be radially deployed to fit the size of the pulmonary vein ostium.
In another aspect of the invention, there is provided a method for treating arrhythmia, including providing a tissue ablation device, wherein the device comprises: a catheter body having a proximal portion and a distal portion, wherein the proximal and distal portions define a longitudinal axis; and at least one deployable umbrella body attached to the distal portion of the catheter body, wherein the umbrella body comprises a plurality of splines attached to the catheter body, and at least one ablation element, wherein the at least one ablation element is attached to at least one of the plurality of splines, wherein the umbrella body is adapted to be delivered to a patient""s vasculature in a retracted configuration and is adapted to contact a circumferential region of tissue at a pulmonary vein ostium in a deployed configuration; inserting and advancing the distal end of the catheter body into the vasculature of an individual experiencing arrhythmia; positioning and deploying the umbrella body such that the plurality of splines are circumferentially disposed at the tissue of a pulmonary vein ostium; and activating the ablation element. Such a method can be used for treating atrial fibrillation, atrial tachycardia, and atypical atrial flutters. Generally, the arrhythmia originates at least in part from an arrhythmogenic origin located at or near the pulmonary vein ostium or other venous structure.
According to the invention, ablation elements can be a cryogenic element, an ultrasound element, a light-emitting element, a microwave element, a thermal element, a laser, chemical fluid, or an electrode element. Specifically, an ablation element can be an electrode. An electrode can deliver a radiofrequency signal of, for example, a 500 KHz or a 250 KHz radiofrequency signal for about 30 to about 120 seconds. Electrodes on a tissue ablation device of the invention can deliver a radiofrequency signal at a temperature of about 40xc2x0 C. to about 70xc2x0 C. Because of their configuration, ablation elements can be activated in a focal, segmental or circumferential manner. Methods of the invention also can utilize a monitoring device or sensing elements located on the tissue ablation device. Signals emitted from the monitoring device or sensing elements can be out of phase with signals emitted from the ablation elements.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods and materials are described below. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety. In case of conflict, the present specification, including definitions, will control.
The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the drawings and detailed description, and from the claims.